Effects of linagliptin on renal endothelial function in patients with type 2 diabetes: a randomised clinical trial

Renal adaptation in pre-obesity patients with hypertension

BACKGROUND AND HYPOTHESIS

Obesity aggravates the risk to develop chronic kidney disease in hypertensive patients. Whether pre-obesity already impairs renal function, renal perfusion and intraglomerular hemodynamics in hypertensive patients is unknown.

METHODS

Renal hemodynamic profiles were measured using steady state input clearance (infusion of para-amino-hippuric acid and inulin) in 36 patients with primary arterial hypertension stage 1-2 without antihypertensive medication. Intraglomerular pressure (IGP) and resistances of the afferent (RA) and efferent (RE) arterioles were calculated. The study population was divided into two groups based on median of waist circumference (WC) (96 cm) (pre-obesity and non-obesity group1) and median of body mass index (BMI) (26.5 kg/m2) (pre-obesity and non-obesity group2), respectively.

RESULTS

All patients were males, non-smoking, aged 36 ± 10 years, with an office blood pressure of 145 ± 8.6/89 ± 11.8 mmHg. None of the patients had cardiovascular disease. Patients from the pre-obese group 1 showed lower glomerular filtration rate (GFR), lower renal plasma flow (RPF) and lower IGP compared to the non-obese group1. Renal vascular resistance (RVR) and RA were higher in the pre-obese group1 compared to the non-obese group1. Similar differences in the hemodynamic profile were found for patients in the pre-obesity group2 compared to the non-obesity group2.

CONCLUSION

The renal hemodynamic profile in hypertensive patients with pre-obesity, irrespective whether defined by WC or BMI, was characterized by a reduced GFR and RPF and by an increased RVR preferentially at the preglomerular site. Our results suggest that hypofiltration is the first phase of renal adaptation in pre-obesity hypertension.

CLINICAL TRIAL REGISTRATION

www.clinicaltrials.gov: NCT02783456.

Is GFR decline induced by SGLT2 inhibitor of clinical importance?

BACKGROUND

Use of sodium-glucose-cotransporter-2 (SGLT2) inhibitors often causes an initial decline in glomerular filtration rate (GFR). This study addresses the question whether the initial decline of renal function with SGLT2 inhibitor treatment is related to vascular changes in the systemic circulation.

METHODS

We measured GFR (mGFR) and estimated GFR (eGFR) in 65 patients with type 2 diabetes (T2D) at baseline and after 12 weeks of treatment randomized either to a combination of empagliflozin and linagliptin (SGLT2 inhibitor based treatment group) (n = 34) or metformin and insulin (non-SGLT2 inhibitor based treatment group) (n = 31). mGFR was measured using the gold standard clearance technique by constant infusion of inulin. In addition to blood pressure (BP), we measured pulse wave velocity (PWV) under standardized conditions reflecting vascular compliance of large arteries, as PWV is considered to be one of the most reliable vascular parameter of cardiovascular (CV) prognosis.

RESULTS

Both mGFR and eGFR decreased significantly after initiating treatment, but no correlation was found between change in mGFR and change in eGFR in either treatment group (SGLT2 inhibitor based treatment group: r=-0.148, p = 0.404; non-SGLT2 inhibitor based treatment group: r = 0.138, p = 0.460). Noticeably, change in mGFR correlated with change in PWV (r = 0.476, p = 0.005) in the SGLT2 inhibitor based treatment group only and remained significant after adjustment for the change in systolic BP and the change in heart rate (r = 0.422, p = 0.018). No such correlation was observed between the change in eGFR and the change in PWV in either treatment group.

CONCLUSIONS

Our main finding is that after initiating a SGLT2 inhibitor based therapy an exaggerated decline in mGFR was related with improved vascular compliance of large arteries reflecting the pharmacologic effects of SGLT2 inhibitor in the renal and systemic vascular bed. Second, in a single patient with T2D, eGFR may not be an appropriate parameter to assess the true change of renal function after receiving SGLT2 inhibitor based therapy.

TRIAL REGISTRATION

clinicaltrials.gov (NCT02752113).

Effect of DPP-4i inhibitors on renal function in patients with type 2 diabetes mellitus: a systematic review and meta-analysis of randomized controlled trials

AIMS

About 20-40% patients with type 2 diabetes mellitus (T2DM) had an increased risk of developing diabetic nephropathy (DN). Dipeptidyl peptidase-4 inhibitors (DPP-4i) were recommended for treatment of T2DM, while the impact of DPP-4i on renal function remained unclear. This study aimed to explore the effect of DPP-4i on renal parameter of estimated glomerular filtration rate (eGFR) and albumin-to-creatinine ratio (ACR) in T2DM.

METHODS

A systematic search was performed across PubMed, Embase and Cochrane Library. A fixed or random-effects model was used for quantitative synthesis according to the heterogeneity, which was assessed with I2 index. Sensitivity analysis and publication bias were performed with standard methods, respectively.

RESULTS

A total of 17 randomized controlled trials were identified. Administration of DPP-4i produced no significant effect on eGFR (WMD, -0.92 mL/min/1.73m2, 95% CI, -2.04 to 0.19) in diabetic condition. DPP-4i produced a favorable effect on attenuating ACR (WMD, -2.76 mg/g, 95% CI, -5.23 to -0.29) in patients with T2DM. The pooled estimate was stable based on the sensitivity test. No publication bias was observed according to Begg's and Egger's tests.

CONCLUSIONS

Treatment with DPP-4i preserved the renal parameter of eGFR in diabetic condition. Available evidences suggested that administration of DPP-4i produced a favorable effect on attenuating ACR in patients with T2DM. INTERNATIONAL PROSPECTIVE REGISTER FOR SYSTEMATIC REVIEW (PROSPERO) NUMBER: CRD.42020144642.

Similarities and Differences of Vascular Calcification in Diabetes and Chronic Kidney Disease

Presently, the mechanism of occurrence and development of vascular calcification (VC) is not fully understood; a range of evidence suggests a positive association between diabetes mellitus (DM) and VC. Furthermore, the increasing burden of central vascular disease in patients with chronic kidney disease (CKD) may be due, at least in part, to VC. In this review, we will review recent advances in the mechanisms of VC in the context of CKD and diabetes. The study further unveiled that VC is induced through the stimulation of pro-inflammatory factors, which in turn impairs endothelial function and triggers similar mechanisms in both disease contexts. Notably, hyperglycemia was identified as the distinctive mechanism driving calcification in DM. Conversely, in CKD, calcification is facilitated by mechanisms including mineral metabolism imbalance and the presence of uremic toxins. Additionally, we underscore the significance of investigating vascular alterations and newly identified molecular pathways as potential avenues for therapeutic intervention.

Postprandial renal haemodynamic effects of the dipeptidyl peptidase-4 inhibitor linagliptin versus the sulphonylurea glimepiride in adults with type 2 diabetes (RENALIS): A predefined substudy of a randomized, double-blind trial

AIM

To determine the effect of the dipeptidyl peptidase-4 inhibitor linagliptin on postprandial glomerular hyperfiltration compared with the sulphonylurea glimepiride in adults with type 2 diabetes (T2D).

MATERIALS AND METHODS

In this predefined substudy within a randomized, double-blind, parallel-group, intervention trial, overweight people with T2D without renal impairment were treated with once-daily linagliptin 5 mg (N = 10) or glimepiride 1 mg (N = 13) as an add-on to metformin for 8 weeks. After a standardized liquid protein-rich meal, the glomerular filtration rate (GFR) and effective renal plasma flow were determined by inulin and para-aminohippuric acid clearance, respectively, based on timed urine sampling. Intrarenal haemodynamics were estimated using the Gomez equations. Glucoregulatory/vasoactive hormones, urinary pH and fractional excretions (FE) of sodium, potassium and urea were measured.

RESULTS

Compared with glimepiride, linagliptin increased the postprandial filtration fraction (FF; mean difference 2.1%-point; P = .016) and estimated glomerular hydraulic pressure (mean difference 3.0 mmHg; P = .050), and tended to increase GFR (P = .08) and estimated efferent renal arteriolar resistance (R_E ; P = .08) from baseline to week 8. No differences in FE were noted. Glimepiride reduced HbA1c more than linagliptin (mean difference -0.40%; P = .004), without between-group differences in time-averaged postprandial glucose levels. In the linagliptin group, change in FF correlated with change in mean arterial pressure (R = 0.807; P = .009) and time-averaged mean glucagon (R = 0.782; P = .008), but not with changes in glucose, insulin, intact glucagon-like peptide-1, renin or FE_Na . Change in glucagon was associated with change in R_E (R = 0.830; P = .003).

CONCLUSIONS

In contrast to our hypothesis, compared with glimepiride, linagliptin does not reduce postprandial hyperfiltration, yet appears to increase FF after meal ingestion by increasing blood pressure or R_E .

Can Newer Anti-Diabetic Therapies Delay the Development of Diabetic Nephropathy?

Type 2 diabetes mellitus (T2DM) is progressive in nature and leads to hyperglycemia-associated microvascular and macrovascular complications. Diabetic nephropathy (DN) is one of the most prominent microvascular complication induced by T2DM and is characterized by albuminuria and progressive loss of kidney function. Aggressive management of hyperglycemia and hypertension has been found effective in delaying the development and progression of DN. Although the conventional antidiabetic treatment is effective in the earlier management of hyperglycemia, the progressive loss of beta cells ultimately needs the addition of insulin to the therapy. The emergence of newer antidiabetic agents may address the limitations associated with conventional antidiabetic therapies, which not only improve the glycemic status but also effective in improving cardio-renal outcomes. Nevertheless, the exact role of these agents and their role in minimizing diabetes progression to DN still needs elaboration. The present review aimed to highlights the impact of these newer antidiabetic agents in the management of hyperglycemia and their role in delaying the progression of diabetes to DN/management of DN in patients with T2DM.

Renal hemodynamic effects differ between antidiabetic combination strategies: randomized controlled clinical trial comparing empagliflozin/linagliptin with metformin/insulin glargine

BACKGROUND

Type 2 diabetes causes cardio-renal complications and is treated with different combination therapies. The renal hemodynamics profile of such combination therapies has not been evaluated in detail.

METHODS

Patients (N = 97) with type 2 diabetes were randomized to receive either empagliflozin and linagliptin (E+L group) or metformin and insulin glargine (M+I group) for 3 months. Renal hemodynamics were assessed with para-aminohippuric acid and inulin for renal plasma flow (RPF) and glomerular filtration rate (GFR). Intraglomerular hemodynamics were calculated according the Gomez´ model.

RESULTS

Treatment with E+L reduced GFR (p = 0.003), but RPF remained unchanged (p = 0.536). In contrast, M+I not only reduced GFR (p = 0.001), but also resulted in a significant reduction of RPF (p < 0.001). Renal vascular resistance (RVR) decreased with E+L treatment (p = 0.001) but increased with M+I treatment (p = 0.001). The changes in RPF and RVR were different between the two groups (both p_adjust < 0.001). Analysis of intraglomerular hemodynamics revealed that E+L did not change resistance of afferent arteriole (R_A) (p = 0.116), but diminished resistance of efferent arterioles (R_E) (p = 0.001). In M+I group R_A was increased (p = 0.006) and R_E remained unchanged (p = 0.538). The effects on R_A (p_adjust < 0.05) and on R_E (p_adjust < 0.05) differed between the groups.

CONCLUSIONS

In patients with type 2 diabetes and preserved renal function treatment with M+I resulted in reduction of renal perfusion and increase in vascular resistance, in contrast to treatment with E+I that preserved renal perfusion and reduced vascular resistance. Moreover, different underlying effects on the resistance vessels have been estimated according to the Gomez model, with M+I increasing R_A and E+L predominantly decreasing R_E, which is in contrast to the proposed sodium-glucose cotransporter 2 inhibitor effects.

TRIAL REGISTRATION

The study was registered at www.clinicaltrials.gov (NCT02752113) on April 26, 2016.

Combination of empagliflozin and linagliptin improves blood pressure and vascular function in type 2 diabetes

AIMS

Preserved vascular function represents a key prognostic factor in type 2 diabetes mellitus (T2DM), but data on vascular parameters in this patient cohort are scarce. Patients with T2DM often need more than one drug to achieve optimal glucose control. The aim of this study was to analyse the efficacy of two combination therapies on vascular function in subjects with T2DM.

METHODS AND RESULTS

This prospective, randomized study included 97 subjects with T2DM. Subjects were randomized to either the combination therapy empagliflozin (E) 10 mg with linagliptin (L) 5 mg once daily or metformin (M) 850 or 1000 mg twice daily with insulin glargine (I) once daily. At baseline and after 12 weeks, subjects had peripheral office and 24-h ambulatory blood pressure (BP) measurement and underwent vascular assessment by pulse wave analysis under office and ambulatory conditions. Office, 24-h ambulatory and central BP as well as pulse pressure (PP) decreased after 12 weeks of treatment with E + L, whereas no change was observed in M + I. There were greater decreases in 24-h ambulatory peripheral systolic (between-group difference: -5.2 ± 1.5 mmHg, P = 0.004), diastolic BP (-1.9 ± 1.0 mmHg, P = 0.036), and PP (-3.3 ± 1.0 mmHg, P = 0.007) in E + L than M + I. Central office systolic BP (-5.56 ± 1.9 mmHg, P = 0.009), forward pressure height of the pulse wave (-2.0 ± 0.9 mmHg, P = 0.028), 24-h ambulatory central systolic (-3.6 ± 1.4 mmHg, P = 0.045), diastolic BP (-1.95 ± 1.1 mmHg, P = 0.041), and 24-h pulse wave velocity (-0.14 ± 0.05m/s, P = 0.043) were reduced to a greater extent with E + L.

CONCLUSION

Beyond the effects on glycaemic control, the combination therapy of E + L significantly improved central BP and vascular function compared with the classic combination of M + I.

CLINICALTRIALS.GOV

NCT02752113.

Roles and Mechanisms of Dipeptidyl Peptidase 4 Inhibitors in Vascular Aging

Vascular aging is characterized by alterations in the constitutive properties and biological functions of the blood vessel wall. Endothelial cells (ECs) and vascular smooth muscle cells (VSMCs) are indispensability elements in the inner layer and the medial layer of the blood vessel wall, respectively. Dipeptidyl peptidase-4 (DPP4) inhibitors, as a hypoglycemic agent, play a protective role in reversing vascular aging regardless of their effects in meliorating glycemic control in humans and animal models of type 2 diabetes mellitus (T2DM) through complex cellular mechanisms, including improving EC dysfunction, promoting EC proliferation and migration, alleviating EC senescence, obstructing EC apoptosis, suppressing the proliferation and migration of VSMCs, increasing circulating endothelial progenitor cell (EPC) levels, and preventing the infiltration of mononuclear macrophages. All of these showed that DPP4 inhibitors may exert a positive effect against vascular aging, thereby preventing vascular aging-related diseases. In the current review, we will summarize the cellular mechanism of DPP4 inhibitors regulating vascular aging; moreover, we also intend to compile the roles and the promising therapeutic application of DPP4 inhibitors in vascular aging-related diseases.

Effects of DPP-4 Inhibitor Linagliptin Versus Sulfonylurea Glimepiride as Add-on to Metformin on Renal Physiology in Overweight Patients With Type 2 Diabetes (RENALIS): A Randomized, Double-Blind Trial

OBJECTIVE

To compare effects of the dipeptidyl peptidase 4 (DPP-4) inhibitor linagliptin with those of a sulfonylurea on renal physiology in metformin-treated patients with type 2 diabetes mellitus (T2DM).

RESEARCH DESIGN AND METHODS

In this double-blind randomized trial, 46 overweight T2DM patients without renal impairment received once-daily linagliptin (5 mg) or glimepiride (1 mg) for 8 weeks. Fasting glomerular filtration rate (GFR) and effective renal plasma flow (ERPF) were determined by inulin and para-aminohippuric acid clearances. Fractional excretions, urinary damage markers, and circulating DPP-4 substrates (among others, glucagon-like peptide 1 and stromal cell-derived factor-1α [SDF-1α]) were measured.

RESULTS

HbA_1c reductions were similar with linagliptin (-0.45 ± 0.09%) and glimepiride (-0.65 ± 0.10%) after 8 weeks (P = 0.101). Linagliptin versus glimepiride did not affect GFR, ERPF, estimated intrarenal hemodynamics, or damage markers. Only linagliptin increased fractional excretion (FE) of sodium (FE_Na) and potassium, without affecting FE of lithium. Linagliptin-induced change in FE_Na correlated with SDF-1α (R = 0.660) but not with other DPP-4 substrates.

CONCLUSIONS

Linagliptin does not affect fasting renal hemodynamics compared with glimepiride in T2DM patients. DPP-4 inhibition promotes modest natriuresis, possibly mediated by SDF-1α, likely distal to the macula densa.

More than just an enzyme: Dipeptidyl peptidase-4 (DPP-4) and its association with diabetic kidney remodelling

PURPOSE OF THE REVIEW

This review article discusses recent advances in the mechanism of dipeptidyl peptidase-4 (DPP-4) actions in renal diseases, especially diabetic kidney fibrosis, and summarizes anti-fibrotic functions of various DPP-4 inhibitors in diabetic nephropathy (DN).

RECENT FINDINGS

DN is a common complication of diabetes and is a leading cause of the end-stage renal disease (ESRD). DPP-4 is a member of serine proteases, and more than 30 substrates have been identified that act via several biochemical messengers in a variety of tissues including kidney. Intriguingly, DPP-4 actions on the diabetic kidney is a complex mechanism, and a variety of pathways are involved including increasing GLP-1/SDF-1, disrupting AGE-RAGE pathways, and integrin-β- and TGF-β-Smad-mediated signalling pathways that finally lead to endothelial to mesenchymal transition. Interestingly, an array of DPP-4 inhibitors is well recognized as oral drugs to treat type 2 diabetic (T2D) patients, which promote better glycemic control. Furthermore, recent experimental and preclinical data reveal that DPP-4 inhibitors may also exhibit protective effects in renal disease progression including anti-fibrotic effects in the diabetic kidney by attenuating above signalling cascade(s), either singly or as a combinatorial effect. In this review, we discussed the anti-fibrotic effects of DPP-4 inhibitors based on recent reports along with the possible mechanism of actions and future perspectives to underscore the beneficial effects of DPP-4 inhibitors in DN.

SUMMARY

With recent experimental, preclinical, and clinical evidence, we summarized DPP-4 activities and its mechanism of actions in diabetic kidney diseases. A knowledge gap of DPP-4 inhibition in controlling renal fibrosis in DN has also been postulated in this review for future research perspectives.

Using DPP-4 inhibitors to modulate beta cell function in type 1 diabetes and in the treatment of diabetic kidney disease

INTRODUCTION

DPP-4 inhibitors have pleomorphic effects that extend beyond the anti-hyperglycemic labeled use of the drug. DPP-4 inhibitors have demonstrated promising renal protective effects in T2DM and T1DM and protective effects against immune destruction of pancreatic beta-cells in T1DM.

AREAS COVERED

The efficacy of DPP-4 inhibitors in the treatment of diabetic kidney disease and possible adjunct with insulin in the treatment of T1DM to preserve beta-cell function. Pertinent literature was identified through Medline, PubMed and ClinicalTrials.gov (1997-November 2018) using the search terms T1DM, sitagliptin, vildagliptin, linagliptin, beta-cell function, diabetic nephropathy. Only articles are written in the English language, and clinical trials evaluating human subjects were used.

EXPERT OPINION

DPP-4 inhibitors can be used safely in patients with diabetic kidney disease and do not appear to exacerbate existing diabetic nephropathy. Linagliptin reduces albuminuria and protects renal endothelium from the deleterious effects of hyperglycemia. The effects of DPP-4 inhibitors on preserving beta-cell function in certain subtypes of T1DM [e.g. Latent Autoimmune Diabetes in Adult (LADA) and Slowly Progressive Type 1 Diabetes (SPIDDM)] are encouraging and show promise.

Clinical Trials on Diabetic Nephropathy: A Cross-Sectional Analysis

INTRODUCTION

Treatment options and decisions are often based on the results of clinical trials. We have evaluated the public availability of results from completed, registered phase III clinical trials on diabetic nephropathy and current treatment options.

METHODS

This was a cross-sectional analysis in which STrengthening the Reporting of OBservational studies in Epidemiology criteria were applied for design and analysis. In June 2017, 34 completed phase III clinical trials on diabetic nephropathy in the ClinicalTrials. gov registry were identified and matched to publications in the ClinicalTrials.gov registry and to those in the PubMed and Google Scholar databases. If no publication was identified, the principal investigator was contacted. The ratio of published and non-published studies was calculated. Various parameters, including study design, drugs, and comparators provided, were analyzed.

RESULTS

Drugs/supplements belonged to 26 different categories of medications, with the main ones being angiotensin-converting enzyme inhibitors, angiotensin-II receptors blockers, and dipeptidyl-peptidase-4-inhibitors. Among the trials completed before 2016 (n = 32), 22 (69%) were published, and ten (31%) remained unpublished. Thus, data on 11 different interventions and more than 1000 patients remained undisclosed. Mean time to publication was 26.5 months, which is longer than the time constrictions imposed by the U.S. Food and Drug Administration Amendments Act. Most trials only showed weak effects on micro- and macroalbuminuria, with an absolute risk reduction of 1.0 and 0.3%, respectively, and the number needed to treat varied between 91 and 333, without any relevant effect on end-stage-renal disease by intensive glucose-lowering treatment. Comparison of the results, however, was difficult since study design, interventions, and the renal outcome parameters vary greatly between the studies.

CONCLUSION

Despite the financial and human resources involved and the relevance for therapeutic guidelines and clinical decisions, about one-third of phase III clinical trials on diabetic nephropathy remain unpublished. Interventions used in published trials showed a low efficacy on renal outcome.

FUNDING

Deutsche Forschungsgemeinschaft (DFG): SFB 1118.

Insulin and glucose-lowering agents for treating people with diabetes and chronic kidney disease

BACKGROUND

Diabetes is the commonest cause of chronic kidney disease (CKD). Both conditions commonly co-exist. Glucometabolic changes and concurrent dialysis in diabetes and CKD make glucose-lowering challenging, increasing the risk of hypoglycaemia. Glucose-lowering agents have been mainly studied in people with near-normal kidney function. It is important to characterise existing knowledge of glucose-lowering agents in CKD to guide treatment.

OBJECTIVES

To examine the efficacy and safety of insulin and other pharmacological interventions for lowering glucose levels in people with diabetes and CKD.

SEARCH METHODS

We searched the Cochrane Kidney and Transplant Register of Studies up to 12 February 2018 through contact with the Information Specialist using search terms relevant to this review. Studies in the Register are identified through searches of CENTRAL, MEDLINE, and EMBASE, conference proceedings, the International Clinical Trials Register (ICTRP) Search Portal and ClinicalTrials.gov.

SELECTION CRITERIA

All randomised controlled trials (RCTs) and quasi-RCTs looking at head-to-head comparisons of active regimens of glucose-lowering therapy or active regimen compared with placebo/standard care in people with diabetes and CKD (estimated glomerular filtration rate (eGFR) < 60 mL/min/1.73 m2) were eligible.

DATA COLLECTION AND ANALYSIS

Four authors independently assessed study eligibility, risk of bias, and quality of data and performed data extraction. Continuous outcomes were expressed as post-treatment mean differences (MD). Adverse events were expressed as post-treatment absolute risk differences (RD). Dichotomous clinical outcomes were presented as risk ratios (RR) with 95% confidence intervals (CI).

MAIN RESULTS

Forty-four studies (128 records, 13,036 participants) were included. Nine studies compared sodium glucose co-transporter-2 (SGLT2) inhibitors to placebo; 13 studies compared dipeptidyl peptidase-4 (DPP-4) inhibitors to placebo; 2 studies compared glucagon-like peptide-1 (GLP-1) agonists to placebo; 8 studies compared glitazones to no glitazone treatment; 1 study compared glinide to no glinide treatment; and 4 studies compared different types, doses or modes of administration of insulin. In addition, 2 studies compared sitagliptin to glipizide; and 1 study compared each of sitagliptin to insulin, glitazars to pioglitazone, vildagliptin to sitagliptin, linagliptin to voglibose, and albiglutide to sitagliptin. Most studies had a high risk of bias due to funding and attrition bias, and an unclear risk of detection bias.Compared to placebo, SGLT2 inhibitors probably reduce HbA1c (7 studies, 1092 participants: MD -0.29%, -0.38 to -0.19 (-3.2 mmol/mol, -4.2 to -2.2); I2 = 0%), fasting blood glucose (FBG) (5 studies, 855 participants: MD -0.48 mmol/L, -0.78 to -0.19; I2 = 0%), systolic blood pressure (BP) (7 studies, 1198 participants: MD -4.68 mmHg, -6.69 to -2.68; I2 = 40%), diastolic BP (6 studies, 1142 participants: MD -1.72 mmHg, -2.77 to -0.66; I2 = 0%), heart failure (3 studies, 2519 participants: RR 0.59, 0.41 to 0.87; I2 = 0%), and hyperkalaemia (4 studies, 2788 participants: RR 0.58, 0.42 to 0.81; I2 = 0%); but probably increase genital infections (7 studies, 3086 participants: RR 2.50, 1.52 to 4.11; I2 = 0%), and creatinine (4 studies, 848 participants: MD 3.82 μmol/L, 1.45 to 6.19; I2 = 16%) (all effects of moderate certainty evidence). SGLT2 inhibitors may reduce weight (5 studies, 1029 participants: MD -1.41 kg, -1.8 to -1.02; I2 = 28%) and albuminuria (MD -8.14 mg/mmol creatinine, -14.51 to -1.77; I2 = 11%; low certainty evidence). SGLT2 inhibitors may have little or no effect on the risk of cardiovascular death, hypoglycaemia, acute kidney injury (AKI), and urinary tract infection (low certainty evidence). It is uncertain whether SGLT2 inhibitors have any effect on death, end-stage kidney disease (ESKD), hypovolaemia, fractures, diabetic ketoacidosis, or discontinuation due to adverse effects (very low certainty evidence).Compared to placebo, DPP-4 inhibitors may reduce HbA1c (7 studies, 867 participants: MD -0.62%, -0.85 to -0.39 (-6.8 mmol/mol, -9.3 to -4.3); I2 = 59%) but may have little or no effect on FBG (low certainty evidence). DPP-4 inhibitors probably have little or no effect on cardiovascular death (2 studies, 5897 participants: RR 0.93, 0.77 to 1.11; I2 = 0%) and weight (2 studies, 210 participants: MD 0.16 kg, -0.58 to 0.90; I2 = 29%; moderate certainty evidence). Compared to placebo, DPP-4 inhibitors may have little or no effect on heart failure, upper respiratory tract infections, and liver impairment (low certainty evidence). Compared to placebo, it is uncertain whether DPP-4 inhibitors have any effect on eGFR, hypoglycaemia, pancreatitis, pancreatic cancer, or discontinuation due to adverse effects (very low certainty evidence).Compared to placebo, GLP-1 agonists probably reduce HbA1c (7 studies, 867 participants: MD -0.53%, -1.01 to -0.06 (-5.8 mmol/mol, -11.0 to -0.7); I2 = 41%; moderate certainty evidence) and may reduce weight (low certainty evidence). GLP-1 agonists may have little or no effect on eGFR, hypoglycaemia, or discontinuation due to adverse effects (low certainty evidence). It is uncertain whether GLP-1 agonists reduce FBG, increase gastrointestinal symptoms, or affect the risk of pancreatitis (very low certainty evidence).Compared to placebo, it is uncertain whether glitazones have any effect on HbA1c, FBG, death, weight, and risk of hypoglycaemia (very low certainty evidence).Compared to glipizide, sitagliptin probably reduces hypoglycaemia (2 studies, 551 participants: RR 0.40, 0.23 to 0.69; I2 = 0%; moderate certainty evidence). Compared to glipizide, sitagliptin may have had little or no effect on HbA1c, FBG, weight, and eGFR (low certainty evidence). Compared to glipizide, it is uncertain if sitagliptin has any effect on death or discontinuation due to adverse effects (very low certainty).For types, dosages or modes of administration of insulin and other head-to-head comparisons only individual studies were available so no conclusions could be made.

AUTHORS' CONCLUSIONS

Evidence concerning the efficacy and safety of glucose-lowering agents in diabetes and CKD is limited. SGLT2 inhibitors and GLP-1 agonists are probably efficacious for glucose-lowering and DPP-4 inhibitors may be efficacious for glucose-lowering. Additionally, SGLT2 inhibitors probably reduce BP, heart failure, and hyperkalaemia but increase genital infections, and slightly increase creatinine. The safety profile for GLP-1 agonists is uncertain. No further conclusions could be made for the other classes of glucose-lowering agents including insulin. More high quality studies are required to help guide therapeutic choice for glucose-lowering in diabetes and CKD.

Impact of dipeptidyl-peptidase 4 inhibitors on cardiovascular diseases

Dipeptidyl peptidase 4 (DPP-4) inhibitor is a novel group of medicine employed in type 2 diabetes mellitus (T2DM),which improves meal stimulated insulin secretion by protecting glucagon-like peptide-1 (GLP-1) and glucose dependent insulinotropic polypeptide (GIP) from enzymatic degradation. Cardiovascular diseases are serious complications and leading causes of mortality among individuals with diabetes mellitus. Glycemic control per se seems to fail in preventing the progression of diabetic cardiovascular complications. DPP-4 has the capability to inactivate not only incretins, but also a series of cytokines, chemokines, and neuropeptides involved in inflammation, immunity, and vascular function. Pre-clinical studies suggested that DPP-4 inhibitors may have potential cardiovascular protective effects in addition to their antidiabetic actions. In recent years, a number of clinical trials have been conducted to evaluate the effect of different DPP-4 inhibitors on the cardiovascular system. We herein review the available clinical studies in cardiovascular effects played by each DPP-4 inhibitor and discuss the prospective application of DPP-4 inhibitors on cardiovascular diseases.

Effects of linagliptin on endothelial function and postprandial lipids in coronary artery disease patients with early diabetes: a randomized, placebo-controlled, double-blind trial

Background

Early glucose lowering intervention in subjects with type 2 diabetes mellitus was demonstrated to be beneficial in terms of micro- and macrovascular risk reduction. However, most of currently ongoing cardiovascular outcome trials are performed in subjects with manifest atherosclerosis and long-standing diabetes. Therefore, the aim of this study is to investigate the effects of the dipeptidylpeptidase-4 inhibitor linagliptin in subjects with coronary artery disease (CAD) but early type 2 diabetes mellitus (T2DM) on a set of cardiovascular surrogate measurements.

Methods

In this randomized, placebo-controlled, double-blind, single-center study, we included subjects with early diabetes (postchallenge diabetes (2 h glucose > 200 mg/dl) or T2DM treated with diet only or on a stable dose of metformin monotherapy and an HbA1c < 75 mmol/mol) and established CAD. Participants were randomized to receive either linagliptin (5 mg) once daily orally or placebo for 12 weeks. The primary outcome was the change in flow mediated dilatation (FMD). The secondary objective was to investigate the effect of linagliptin treatment on arginine bioavailability ratios [Global arginine bioavailability ratio (GABR) and arginine to ornithine ratio (AOR)]. Arginine, ornithine and citrulline were measured in serum samples with a conventional usual amino acid analysis technique, involving separation of amino acids by ion exchange chromatography followed by postcolumn continuous reaction with ninhydrin. GABR was calculated by l-arginine divided by the sum of (l-ornithine plus l-citrulline). The AOR was calculated by dividing l-arginine by l-ornithine levels. Group comparisons were calculated by using a two-sample t-test with Satterthwaite adjustment for unequal variances.

Results

We investigated 43 patients (21% female) with a mean age of 63.3 ± 8.2 years. FMD at baseline was 3.5 ± 3.1% in the linagliptin group vs. 4.0 ± 2.9% in the placebo group. The change in mean FMD in the linagliptin group was not significantly different compared to the change in the placebo group (0.43 ± 4.84% vs. − 0.45 ± 3.01%; p = 0.486). No significant improvements were seen in the arginine bioavailability ratios (GABR; p = 0.608 and AOR; p = 0.549).

Conclusion

Linagliptin treatment in subjects with CAD and early T2DM did not improve endothelial function or the arginine bioavailability ratios.

Trial registration ClinicalTrials.gov, NCT02350478 (https://clinicaltrials.gov/ct2/show/NCT02350478)

Electronic supplementary material

The online version of this article (10.1186/s12933-018-0716-x) contains supplementary material, which is available to authorized users.

The role of dipeptidylpeptidase-4 inhibitors in management of cardiovascular disease in diabetes; focus on linagliptin

Multiple population based analyses have demonstrated a high incidence of cardiovascular disease (CVD) and cardiovascular (CV) mortality in subjects with T2DM that reduces life expectancy by as much as 15 years. Importantly, the CV system is particularly sensitive to the metabolic and immune derangements present in obese pre-diabetic and diabetic individuals; consequently, CV dysfunction is often the initial CV derangement to occur and promotes the progression to end organ/tissue damage in T2DM. Specifically, diabetic CVD can manifest as microvascular complications, such as nephropathy, retinopathy, and neuropathy, as well as, macrovascular impairments, including ischemic heart disease, peripheral vascular disease, and cerebrovascular disease. Despite some progress in prevention and treatment of CVD, mainly via blood pressure and dyslipidemia control strategies, the impact of metabolic disease on CV outcomes is still a major challenge and persists in proportion to the epidemics of obesity and diabetes. There is abundant pre-clinical and clinical evidence implicating the DPP-4-incretin axis in CVD. In this regard, linagliptin is a unique DPP-4 inhibitor with both CV and renal safety profiles. Moreover, it exerts beneficial CV effects beyond glycemic control and beyond class effects. Linagliptin is protective for both macrovascular and microvascular complications of diabetes in preclinical models, as well as clinical models. Given the role of endothelial-immune cell interactions as one of the key events in the initiation and progression of CVD, linagliptin modulates these cell–cell interactions by affecting two important pathways involving stimulation of NO signaling and potent inhibition of a key immunoregulatory molecule.

The role of renal dipeptidyl peptidase-4 in kidney disease: renal effects of dipeptidyl peptidase-4 inhibitors with a focus on linagliptin

Emerging evidence suggests that dipeptidyl peptidase-4 (DPP-4) inhibitors used to treat type 2 diabetes may have nephroprotective effects beyond the reduced renal risk conferred by glycemic control. DPP-4 is a ubiquitous protein with exopeptidase activity that exists in cell membrane-bound and soluble forms. The kidneys contain the highest levels of DPP-4, which is increased in diabetic nephropathy. DPP-4 inhibitors are a chemically heterogeneous class of drugs with important pharmacological differences. Of the globally marketed DPP-4 inhibitors, linagliptin is of particular interest for diabetic nephropathy as it is the only compound that is not predominantly excreted in the urine. Linagliptin is also the most potent DPP-4 inhibitor, has the highest affinity for this protein, and has the largest volume of distribution; these properties allow linagliptin to penetrate kidney tissue and tightly bind resident DPP-4. In animal models of kidney disease, linagliptin elicited multiple renoprotective effects, including reducing albuminuria, glomerulosclerosis, and tubulointerstitial fibrosis, independent of changes in glucagon-like peptide-1 (GLP-1) and glucose levels. At the molecular level, linagliptin prevented the pro-fibrotic endothelial-to-mesenchymal transition by disrupting the interaction between membrane-bound DPP-4 and integrin β1 that enhances signaling by transforming growth factor-β1 and vascular endothelial growth factor receptor-1. Linagliptin also increased stromal cell derived factor-1 levels, ameliorated endothelial dysfunction, and displayed unique antioxidant effects. Although the nephroprotective effects of linagliptin are yet to be translated to the clinical setting, the ongoing Cardiovascular and Renal Microvascular Outcome Study with Linagliptin in Patients with Type 2 Diabetes Mellitus (CARMELINA®) study will definitively assess the renal effects of this DPP-4 inhibitor. CARMELINA® is the only clinical trial of a DPP-4 inhibitor powered to evaluate kidney outcomes.

A review of dipeptidyl peptidase-4 inhibitors. Hot topics from randomized controlled trials

The first clinical study to investigate effects of dipeptidyl peptidase-4 (DPP-4) inhibition was published in 2002, and since then, numerous randomized controlled trials (RCTs) have shown that DPP-4 inhibitors are efficacious, safe and well-tolerated. This review will focus upon RCTs which have investigated DPP-4 inhibitors in patient groups which are often under-represented or excluded from typical phase 3 clinical trials. Large cardiovascular (CV) safety outcome trials in patients with established CV disease have confirmed that DPP-4 inhibitors are not associated with any additional CV risk in these already-at-high-risk individuals, while raising awareness of any uncommon adverse events, such as heart failure hospitalization seen in one of the trials. Studies in patients with kidney disease have shown DPP-4 inhibitors to be efficacious without increasing the risk of hypoglycaemia, irrespective of the degree of renal impairment, while data from the large CV trials as well as smaller RCTs have even pointed towards potential renoprotective effects such individuals. The use of DPP-4 inhibitors with insulin when therapy requires intensification may be beneficial without affecting the incidence or severity of hypoglycaemia, with these effects also being replicated in patients with chronic kidney disease, for whom other agents may not be suitable. Attention is now turning towards exploring the potential utility of DPP-4 inhibitors in other circumstances, including for in-hospital management of hyperglycaemia and in other metabolic disorders. Together, these RCTs raise the possibility that in the future, DPP-4 inhibitors may have a broader use which may extend beyond glycaemic control in the typical type 2 diabetes mellitus (T2DM) patient seen in general practice and may encompass conditions other than T2DM.

GLP-1 and the kidney: from physiology to pharmacology and outcomes in diabetes

The gastrointestinal tract - the largest endocrine network in human physiology - orchestrates signals from the external environment to maintain neural and hormonal control of homeostasis. Advances in understanding entero-endocrine cell biology in health and disease have important translational relevance. The gut-derived incretin hormone glucagon-like peptide 1 (GLP-1) is secreted upon meal ingestion and controls glucose metabolism by modulating pancreatic islet cell function, food intake and gastrointestinal motility, amongst other effects. The observation that the insulinotropic actions of GLP-1 are reduced in type 2 diabetes mellitus (T2DM) led to the development of incretin-based therapies - GLP-1 receptor agonists and dipeptidyl peptidase 4 (DPP-4) inhibitors - for the treatment of hyperglycaemia in these patients. Considerable interest exists in identifying effects of these drugs beyond glucose-lowering, possibly resulting in improved macrovascular and microvascular outcomes, including in diabetic kidney disease. As GLP-1 has been implicated as a mediator in the putative gut-renal axis (a rapid-acting feed-forward loop that regulates postprandial fluid and electrolyte homeostasis), direct actions on the kidney have been proposed. Here, we review the role of GLP-1 and the actions of associated therapies on glucose metabolism, the gut-renal axis, classical renal risk factors, and renal end points in randomized controlled trials of GLP-1 receptor agonists and DPP-4 inhibitors in patients with T2DM.

Diabetes, hypertension, and chronic kidney disease progression: role of DPP4

The protein dipeptidyl peptidase 4 (DPP4) is a target in diabetes management and reduction of associated cardiovascular risk. Inhibition of the enzymatic function and genetic deletion of DPP4 is associated with tremendous benefits to the heart, vasculature, adipose tissue, and the kidney in rodent models of obesity, diabetes and hypertension, and associated complications. The recently concluded, "Saxagliptin Assessment of Vascular Outcomes Recorded in Patients with Diabetes Mellitus-Thrombolysis in Myocardial Infarction 53" trial revealed a reduction in proteinuria in chronic kidney disease patients (stages 1-3). These results have spurred immense interest in the nonenzymatic and enzymatic role of DPP4 in the kidney. DPP4 is expressed predominantly in the glomeruli and S1-S3 segments of the nephron and to a lesser extent in other segments. DPP4 is known to facilitate absorption of cleaved dipeptides and regulate the function of the sodium/hydrogen exchanger-3 in the proximal tubules. DPP4, also known as CD26, has an important role in costimulation of lymphocytes via caveolin-1 on antigen-presenting cells in peripheral blood. Herein, we present our perspectives for the ongoing interest in the role of DPP4 in the kidney.

A randomised, active- and placebo-controlled, three-period crossover trial to investigate short-term effects of the dipeptidyl peptidase-4 inhibitor linagliptin on macro- and microvascular endothelial function in type 2 diabetes

Background

Studies of dipeptidyl peptidase (DPP)-4 inhibitors report heterogeneous effects on endothelial function in patients with type 2 diabetes (T2D). This study assessed the effects of the DPP-4 inhibitor linagliptin versus the sulphonylurea glimepiride and placebo on measures of macro- and microvascular endothelial function in patients with T2D who represented a primary cardiovascular disease prevention population.

Methods

This crossover study randomised T2D patients (n = 42) with glycated haemoglobin (HbA1c) ≤7.5%, no diagnosed macro- or microvascular disease and on stable metformin background to linagliptin 5 mg qd, glimepiride 1–4 mg qd or placebo for 28 days. Fasting and postprandial macrovascular endothelial function, measured using brachial flow-mediated vasodilation, and microvascular function, measured using laser-Doppler on the dorsal thenar site of the right hand, were analysed after 28 days.

Results

Baseline mean (standard deviation) age, body mass index and HbA1c were 60.3 (6.0) years, 30.3 (3.0) kg/m² and 7.41 (0.61)%, respectively. After 28 days, changes in fasting flow-mediated vasodilation were similar between the three study arms (treatment ratio, gMean [90% confidence interval]: linagliptin vs glimepiride, 0.884 [0.633–1.235]; linagliptin vs placebo, 0.884 [0.632–1.235]; glimepiride vs placebo, 1.000 [0.715–1.397]; P = not significant for all comparisons). Similarly, no differences were seen in postprandial flow-mediated vasodilation. However, under fasting conditions, linagliptin significantly improved microvascular function as shown by a 34% increase in hyperaemia area (P = 0.045 vs glimepiride), a 34% increase in resting blow flow (P = 0.011 vs glimepiride, P = 0.003 vs placebo), and a 25% increase in peak blood flow (P = 0.009 vs glimepiride, P = 0.003 vs placebo). There were no significant differences between treatments in postprandial changes. Linagliptin had no effect on heart rate or blood pressure. Rates of overall adverse events with linagliptin, glimepiride and placebo were 27.5, 61.0 and 35.0%, respectively. Fewer hypoglycaemic events were seen with linagliptin (5.0%) and placebo (2.5%) than with glimepiride (39.0%).

Conclusions

Linagliptin had no effect on macrovascular function in T2D, but significantly improved microvascular function in the fasting state.

Trial registration ClinicalTrials.gov identifier—NCT01703286; registered October 1, 2012

Electronic supplementary material

The online version of this article (doi:10.1186/s12933-016-0493-3) contains supplementary material, which is available to authorized users.